The High Command of Air Defense and Air Force on Tuesday ordered all divisions to suspend flight training courses following a military helicopter crash that left 18 dead and three injured in Hanoi.

The high command has raised security protocols to Level 1 – the highest level in the aviation sector.

Divisions are now restricted to only conducting flights for the performance of urgent tasks.

At around 7:50 a.m., on Monday (July 7), a Russian-made MI-171 helicopter from Regiment 916 of 371st Air Force Division fell out of the sky with 21 people on board, including three crew members, two trainers, and 16 soldiers, during a parachuting exercise.

Sixteen people on board were killed instantly and five others were rushed to a nearby hospital suffering from serious burns.

Two more soldiers succumbed to their injuries later that evening, bringing the total fatalities to 18. The three survivors of the crash are still being treated at the National Institute for Burn Victims in Hanoi's Ha Dong District.

The helicopter took off from Hoa Lac military airport in Hanoi’s Ba Vi District and lost contact with its base 16 minutes later.

The helicopter reportedly made landfall near Village 11 in Thach Hoa Commune, Thach That District, around 500 meters away from a market and 40 kilometers west of Hanoi.

The crash site lies around three kilometers from the airbase.

Authorities quickly recovered the helicopter's flight recorder and are investigating the cause of the crash.

On Monday, Lieutenant-General Vo Van Tuan, Deputy Chief of the Army General Staff, told news website VnExpress a “technical error” was to blame for the crash.

He said the crew members had managed to direct the helicopter far from crowded areas as soon as they detected the error.